[Music] despite the appendix having no clear or defined function due to its relative frequency in becoming blocked and pathological it's a structure that we need to have a detailed knowledge of the appendix is a narrow blind-ended tube which is attached to the posterior medial end of the circum the appendix itself is derived from the embryological midgut and appears during the fifth month of gestation the appendix is named vermiform due to its resemblance to a worm which in latin is vermees it does vary in length between individuals and measures between two centimeters to 20 centimeters so it can get surprisingly long but the average length is around 8 to 10 centimeters typically the base of the appendix is located at the point of the cecum where the longitudinal tini e coli converge and by remembering this it gives us an easy way to find the appendix if we're struggling to locate it during surgery the layers of the appendix are similar to those of the large intestine with the outer sarosa layer covering two layers of the muscularis propria an outer fully circumferential longitudinal muscle layer followed by an inner circumferential layer continuing inward the two innermost layers are the submucosa and the mucosal layers the key distinguishing characteristics of the appendix compared to the rest of the large bowel are the presence of a high number of lymphoid aggregates in the submucosa layer which are particularly prominent in adolescence but then diminish gradually with increasing age in terms of the nerves applied to the appendix it's innovated by both sympathetic and parasympathetic branches of the autonomic nervous system which in keeping with the midgar embryological origin of the appendix are carried by the iliocolic branch of the superior esoteric plexus the importance of this nerve distribution and the fact that the sympathetic afferent nerve fibers of the appendix arise at the t10 level of the spinal cord explains why patients with early appendicitis experience an initial visceral pain around the central abdomen which is described as a dull ache before then becoming localized to the rightelic fossa the arterial supply to the appendix is via the appendicular artery and here we can see it branching off the ileocolocartry before running parallel with the appendix within the small messenger of the appendix which we refer to as the mesoappendix the location of the tip the appendix can be highly variable however the position of the base is far more predictable typically we find it at a point two-thirds the distance along a straight line from the umbilicus to the anterior superior iliac spine or asus as we can see demonstrated here we refer to this point as mcburney's point after the 19th century american surgeon charles mcburney who described this point as being the location of maximal tenderness in patients with acute appendicitis and here we can see how it corresponds nicely with the location of the appendix base as we've already mentioned the position of the appendix base is typically found around mcburney's point however there is a relatively high variability in the position of the appendix tip the majority of the time the appendix is located in a retrosequel position so it lies behind the cecum in 20 of cases the tip lies in the patient's pelvis the remaining possible positions are pretty rare with paracetal and subsequent making up two and 1.5 respectively and pre-allele and post allele making up one and point five percent but why do we actually care where the tip lies well the reason we care is that the location and the type of symptoms and signs that the patient experiences is often dependent on where the position this tip lies